1. Field of the Invention
The present invention relates to a land appearance inspecting device and land appearance inspecting method for inspecting an appearance of an amorphous land whose shape is a circle with a protruding portion, such as an LGA (Land Grid Array).
2. Description of the Related Art
Previously, as a land inspecting method, for example, in Japanese unexamined patent publication no. 9-203620, a technique for inspecting a broken neck of a land has been disclosed. More specifically, a center position and radius of a through hole are calculated from image data, and image data of a region including a land is extracted on the basis of the center position and radius. And, on the basis of the extracted image data, an edge of a wiring pattern is resolved and extracted for each predetermined direction component as edge image data, and a shape corresponding to a broken wiring portion is recognized on the basis of a plurality of the extracted edge image data, and a broken neck is determined on the basis of the recognized result.
Also, a technique has been disclosed in, for example, Japanese patent nos. 2502853 and 2502854, in which a wiring pattern and through hole portion are separated from image data, and the through hole portion of the wiring pattern is filled, while arbitrary amount expansion processing is applied to the separated through hole image, and logical operation is performed thereon with the filled binary image, whereby a discrepancy portion is detected as a defect of a land portion of the through hole.
By the way, in integrated circuits, amorphous shape lands are arranged at an equal pitch in a grid form on a package (PKG) reverse surface, which is called an LGA (Land Grid Array). The shape of a land in the LGA has a feature of an amorphous circle with a protruding portion. Since the land has an aligned appearance, position angle inspection (inspection of coordinate position accuracy of a circular portion) is required for mounting, while it is important to detect a foreign body, flaw, and break on the land caused by a resistor failure, contact error and the like.
However, the prior techniques are designed for inspection of the land disposed on a general substrate, and consequently it is substantially impossible to apply them to inspection of the reverse side of an IC called the LGA. Even if the prior land inspecting methods are applied to land inspection of the LGA, detected position accuracy is low, while no break (chip) can be detected in shape inspection.